Question
Let $A$ be a square matrix, then prove thati. $A+A^{T}$ is a symmetric matrixii. $A-A^{T}$ is a skew-symmetric matrixiii. $A A^{T}$ and $A^{T} A$ are symmetric matrices.
Step 1
A matrix is said to be symmetric if its transpose is equal to the matrix itself. So, let's take the transpose of $A+A^{T}$: \[(A+A^{T})^{T} = A^{T} + (A^{T})^{T}\] We know that the transpose of a transpose matrix is the same matrix, so we get: \[(A+A^{T})^{T} = Show more…
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(i) Let $\mathrm{A}$ be a square matrix. Show that $\mathrm{A}+\mathrm{A}^{\mathrm{T}}$ is symmetric, $\mathrm{A}-\mathrm{A}^{\mathrm{T}}$ is skew symmetric (ii) Write $A=\left(\begin{array}{lll}2 & 4 & 5 \\ 6 & 7 & 8 \\ 3 & 2 & 9\end{array}\right)$ as the sum of a symmetric matrix and a skew symmetric matrix.
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